Invalid value for member, Instant Desktop Creation Failed

Recently I was building a quick lab setup for testing VMware Horizon View Instant Clones when I ran into an error message I couldn’t directly “decypher”.

I built a Windows 10 x64 virtual machine on VMware ESX 6.5 and simply named the machine win10. I installed the required tools and software, created a snapshot and switched to the VMware Horizon View Admin Console for creating the instant clones. Using the Add Desktop Pool wizard I provided all necessary details and choose Instant clones. I then provided a naming scheme for the instant clones like this 1709-{n}. I choose 1709according the Windows 10 branch version.

I clicked Finish to start creating the instant clones, when suddenly I received the following error message.

As the error message itself didn’t really give me an idea why there really was an error, I decided to dig a bit deeper in the debug logs. These logs can be found on the Connection Server in C:\ProgramData\VMware\VDM\logs.

Opening the debug log and trying to find what went wrong, I still didn’t find a clue for what went wrong. I only found the same message Invalid value for member, Instant Desktop Creation Failed.

At first I didn’t find an extensive message that explains (a bit) more. Until I found the following message in this same debug log.

Now, this gave me a usable hint and I reviewed the Naming Pattern for Automated Desktop Pools documentation. Reading the documentation I didn’t find a reason why it failed on the naming pattern. Therefore I decided to change the naming pattern and not use 1709-{n}, but simply win10-{n}. Using this naming pattern resulted in the successful creation of instant clones without any error messages.

The conclusion is that you cannot use a naming pattern that only uses numbers. I didn’t know this and found out the hard way. Other combinations, like win10-{n} or 123test-{n} can be used.

Ivan de Mes works as an EUC Solution Architect for Login Consultants in The Netherlands. Ivan has over 19 years of experience in delivering workspace solutions at large customers in banking, health care, education and others.